Narrowband positioning signal design and procedures

ABSTRACT

Certain aspects of the present disclosure generally relate to downlink (DL) based and uplink (UL) based positioning reference signal (PRS) techniques that may help facilitate positioning procedures in systems deploying narrowband devices, such as narrowband Internet of Things (NB-IoT) devices. An exemplary method that may be performed by a node includes monitoring for positioning reference signals (PRS) transmitted from one or more base stations within a narrowband region of a wider system bandwidth, wherein tones of the PRS are repeated across at least one of multiple symbols within a same subframe, or multiple consecutive subframes, and estimating timing from the one or more base stations based on the PRS.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application for patent claims priority to U.S. ProvisionalApplication No. 62/338,475, filed May 18, 2016, which is assigned to theassignee of the present application and hereby expressly incorporated byreference herein in its entirety.

BACKGROUND Field of the Invention

Certain aspects of the present disclosure generally relate to wirelesscommunications and more specifically to positioning in wirelesscommunications systems that utilize narrowband regions of wider systembandwidth.

Description of Related Art

Wireless communication systems are widely deployed to provide varioustypes of communication content such as voice, data, and so on. Thesesystems may be multiple-access systems capable of supportingcommunication with multiple users by sharing the available systemresources (e.g., bandwidth and transmit power). Examples of suchmultiple-access systems include code division multiple access (CDMA)systems, time division multiple access (TDMA) systems, frequencydivision multiple access (FDMA) systems, 3rd Generation PartnershipProject (3GPP) Long Term Evolution (LTE) including LTE-Advanced systemsand orthogonal frequency division multiple access (OFDMA) systems.

Generally, a wireless multiple-access communication system cansimultaneously support communication for multiple wireless terminals.Each terminal communicates with one or more base stations viatransmissions on the forward and reverse links. The forward link (ordownlink) refers to the communication link from the base stations to theterminals, and the reverse link (or uplink) refers to the communicationlink from the terminals to the base stations. This communication linkmay be established via a single-input single-output, multiple-inputsingle-output or a multiple-input multiple-output (MIMO) system.

A wireless communication network may include a number of base stationsthat can support communication for a number of wireless devices.Wireless devices may include user equipments (UEs). Some UEs may beconsidered machine type communication (MTC) UEs, which may includeremote devices, that may communicate with a base station, another remotedevice, or some other entity. Machine type communications (MTC) mayrefer to communication involving at least one remote device on at leastone end of the communication and may include forms of data communicationwhich involve one or more entities that do not necessarily need humaninteraction. MTC UEs may include UEs that are capable of MTCcommunications with MTC servers and/or other MTC devices through PublicLand Mobile Networks (PLMN), for example.

In some cases devices, such as MTC and other types of devices, maycommunicate using a narrowband (NB) region of wider system bandwidth.Utilizing a narrowband region may present challenges for variousprocedures, such as positioning procedures where positioning referencesignals are used to track a location (and/or movement) of devices withina network.

SUMMARY

The systems, methods, and devices of the disclosure each have severalaspects, no single one of which is solely responsible for its desirableattributes. Without limiting the scope of this disclosure as expressedby the claims which follow, some features will now be discussed briefly.After considering this discussion, and particularly after reading thesection entitled “Detailed Description” one will understand how thefeatures of this disclosure provide advantages that include improvedcommunications between access points and stations in a wireless network.

Aspects of the present disclosure provide a method for wirelesscommunications performed by a wireless node. The method generallyincludes monitoring for positioning reference signals (PRS) transmitted,from one or more base stations, within a narrowband region of widersystem bandwidth and estimating timing from the one or more basestations based on the PRS.

Aspects of the present disclosure provide a method for wirelesscommunications performed by a base station. The method generallyincludes monitoring for positioning reference signals (PRS) transmitted,from at least one wireless node, within a narrowband region of widersystem bandwidth and estimating timing from the at least one wirelessnode based on the PRS.

Aspects of the present disclosure provide a method for wirelesscommunications performed by a wireless node. The method generallyincludes determining resources within a narrowband region of widersystem bandwidth for transmitting positioning reference signals (PRS) toone or more base stations and transmitting the PRS using the determinedresources.

Aspects of the present disclosure provide a method for wirelesscommunications performed by a base station. The method generallyincludes determining resources within a narrowband region of widersystem bandwidth for transmitting downlink positioning reference signals(PRS) to one or more wireless nodes and transmitting the downlink PRSusing the determined resources.

Aspects of the present disclosure provide a method for wirelesscommunications performed by a wireless node. The method generallyincludes monitoring for positioning reference signals (PRS) transmitted,from one or more base stations, across a plurality of narrowband regionswithin a wider system bandwidth and estimating at least one of downlinktiming or relative location of the wireless node based on the PRS.

Aspects of the present disclosure provide a method for wirelesscommunications performed by a wireless node. The method generallyincludes determining resources in a plurality of narrowband regionswithin wider system bandwidth for transmitting positioning referencesignals (PRS) to one or more base stations and transmitting the PRSusing the determined resources.

Aspects of the present disclosure provide a method for wirelesscommunications performed by a base station. The method generallyincludes monitoring for positioning reference signals (PRS) transmitted,from a wireless node, across a plurality of narrowband regions within awider system bandwidth and estimating at least one of uplink timing orrelative location of the wireless node based on the PRS.

Aspects of the present disclosure provide a method for wirelesscommunications performed by a base station. The method generallyincludes determining resources in a plurality of narrowband regionswithin wider system bandwidth for transmitting positioning referencesignals (PRS) to at least one wireless node and transmitting the PRSusing the determined resources

Numerous other aspects are provided including methods, apparatus,systems, computer program products, computer readable medium, andprocessing systems.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the above-recited features of the presentdisclosure can be understood in detail, a more particular description,briefly summarized above, may be had by reference to aspects, some ofwhich are illustrated in the appended drawings. It is to be noted,however, that the appended drawings illustrate only certain typicalaspects of this disclosure and are therefore not to be consideredlimiting of its scope, for the description may admit to other equallyeffective aspects.

FIG. 1 is a block diagram conceptually illustrating an example wirelesscommunication network, in accordance with certain aspects of the presentdisclosure.

FIG. 2 is a block diagram conceptually illustrating an example of anevolved nodeB (eNB) in communication with a user equipment (UE) in awireless communications network, in accordance with certain aspects ofthe present disclosure.

FIG. 3 is a block diagram conceptually illustrating an example framestructure for a particular radio access technology (RAT) for use in awireless communications network, in accordance with certain aspects ofthe present disclosure.

FIG. 4 illustrates example subframe formats for the downlink with anormal cyclic prefix, in accordance with certain aspects of the presentdisclosure.

FIGS. 5A and 5B illustrate an example of MTC co-existence within awideband system, such as LTE, in accordance with certain aspects of thepresent disclosure.

FIG. 6 illustrates an exemplary mapping of DL narrowband regions to ULnarrowband regions, in accordance with certain aspects of the presentdisclosure.

FIG. 7 illustrates example positioning reference signal (PRS) toneswithin a physical resource block (PRB), in accordance with certainaspects of the present disclosure.

FIG. 8 illustrates example PRS tones within a PRB with hopping acrosssubframes, in accordance with certain aspects of the present disclosure.

FIG. 9 illustrates example PRS with a single tone with hopping acrosssubframes, in accordance with certain aspects of the present disclosure.

FIG. 10 illustrates example operations for downlink-based narrowband PRSthat may be performed by a BS, in accordance with certain aspects of thepresent disclosure.

FIG. 10A illustrates example means capable of performing the operationsshown in FIG. 10.

FIG. 11 illustrates example operations for downlink-based narrowband PRSthat may be performed by a wireless node, in accordance with certainaspects of the present disclosure.

FIG. 11A illustrates example means capable of performing the operationsshown in FIG. 11.

FIG. 12 illustrates example operations for uplink-based narrowband PRSthat may be performed by a wireless node, in accordance with certainaspects of the present disclosure.

FIG. 12A illustrates example means capable of performing the operationsshown in FIG. 12.

FIG. 13 illustrates example operations for uplink-based narrowband PRSthat may be performed by a BS, in accordance with certain aspects of thepresent disclosure.

FIG. 13A illustrates example means capable of performing the operationsshown in FIG. 13.

FIG. 14 illustrates example operations for downlink-based PRS acrossmultiple narrowbands that may be performed by a BS, in accordance withcertain aspects of the present disclosure.

FIG. 14A illustrates example means capable of performing the operationsshown in FIG. 14.

FIG. 15 illustrates example operations for downlink-based narrowband PRSacross multiple narrowbands that may be performed by a wireless node, inaccordance with certain aspects of the present disclosure.

FIG. 15A illustrates example means capable of performing the operationsshown in FIG. 15.

FIG. 16 illustrates example operations for uplink-based narrowband PRSacross multiple narrowbands that may be performed by a wireless node, inaccordance with certain aspects of the present disclosure.

FIG. 16A illustrates example means capable of performing the operationsshown in FIG. 16.

FIG. 17 illustrates example operations for uplink-based narrowband PRSacross multiple narrowbands that may be performed by a BS, in accordancewith certain aspects of the present disclosure.

FIG. 17A illustrates example means capable of performing the operationsshown in FIG. 17.

DETAILED DESCRIPTION

Aspects of the present disclosure provide techniques and apparatus forpositioning for devices with limited communication resources, such aslow cost (LC) machine type communication (MTC) devices, LC enhanced MTC(eMTC) devices, narrowband Internet of Things (IoT) devices, and thelike. As will be described herein, positioning reference signals (PRS)may be transmitted by a wireless node (to one or more base stations) inone or more narrowband regions of overall system bandwidth foruplink-based PRS positioning. Similarly, narrowband PRS may betransmitted by one or more base stations, for downlink-based PRSpositioning.

The techniques described herein may be used for various wirelesscommunication networks such as Code Division Multiple Access (CDMA)networks, Time Division Multiple Access (TDMA) networks, FrequencyDivision Multiple Access (FDMA) networks, Orthogonal FDMA (OFDMA)networks, Single-Carrier FDMA (SC-FDMA) networks, etc. The terms“network” and “system” are often used interchangeably. A CDMA networkmay implement a radio technology such as Universal Terrestrial RadioAccess (UTRA), cdma2000, etc. UTRA includes Wideband-CDMA (W-CDMA), TimeDivision Synchronous CDMA (TD-SCDMA), and other variants of CDMA.cdma2000 covers IS-2000, IS-95 and IS-856 standards. A TDMA network mayimplement a radio technology such as Global System for MobileCommunications (GSM). An OFDMA network may implement a radio technologysuch as Evolved UTRA (E-UTRA), Ultra Mobile Broadband (UMB), IEEE 802.11(Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802.20, Flash-OFDM®, etc. UTRA andE-UTRA are part of Universal Mobile Telecommunication System (UMTS).3GPP Long Term Evolution (LTE) and LTE-Advanced (LTE-A), in bothfrequency division duplex (FDD) and time division duplex (TDD), arereleases of UMTS that use E-UTRA, which employs OFDMA on the downlinkand SC-FDMA on the uplink. UTRA, E-UTRA, UMTS, LTE, LTE-A and GSM aredescribed in documents from an organization named “3rd GenerationPartnership Project” (3GPP). cdma2000 and UMB are described in documentsfrom an organization named “3rd Generation Partnership Project 2”(3GPP2). New radio (NR), which may also be referred to as 5G, is a setof enhancements to the LTE mobile standard promulgated by ThirdGeneration Partnership Project (3GPP). The techniques described hereinmay be used for the wireless networks and radio technologies mentionedabove as well as other wireless networks and radio technologies. Forclarity, certain aspects of the techniques are described below forLTE/LTE-A, and LTE/LTE-A terminology is used in much of the descriptionbelow. LTE and LTE-A are referred to generally as LTE.

FIG. 1 illustrates an example wireless communication network 100 withbase stations (BSs) and user equipments (UEs), in which aspects of thepresent disclosure may be practiced.

For example, one or more paging procedure enhancements for certain UEs(e.g., LC MTC UEs, LC eMTC UEs, etc.) in the wireless communicationnetwork 100 may be supported. According to the techniques presentedherein, the BSs and LC UE(s) in the wireless communication network 100may be able to determine, from the available system bandwidth supportedby the wireless communication network 100, which narrowband region(s)the LC UE(s) should monitor for a bundled paging message transmittedfrom the BSs in the wireless communication network 100. Also, accordingto techniques presented herein, the BSs and/or LC UE(s) in the wirelesscommunication network 100 may be able to determine and/or adapt thebundling size for the paging message based on one or more triggers inthe wireless communication network 100. A BS may be referred to as aNode B, eNodeB or eNB, gNB, access point (AP), radio head, TRP (transmitreceive point, transmission reception point, etc.), new radio (NR) BS,5G NB, etc.

The wireless communication network 100 may be an LTE network or someother wireless network. Wireless communication network 100 may include anumber of evolved NodeBs (eNBs) 110 and other network entities. An eNBis an entity that communicates with user equipments (UEs) and may alsobe referred to as a base station, a Node B, an access point (AP), etc.Each eNB may provide communication coverage for a particular geographicarea. In 3GPP, the term “cell” can refer to a coverage area of an eNBand/or an eNB subsystem serving this coverage area, depending on thecontext in which the term is used.

An eNB may provide communication coverage for a macro cell, a pico cell,a femto cell, and/or other types of cell. A macro cell may cover arelatively large geographic area (e.g., several kilometers in radius)and may allow unrestricted access by UEs with service subscription. Apico cell may cover a relatively small geographic area and may allowunrestricted access by UEs with service subscription. A femto cell maycover a relatively small geographic area (e.g., a home) and may allowrestricted access by UEs having association with the femto cell (e.g.,UEs in a closed subscriber group (CSG)). An eNB for a macro cell may bereferred to as a macro eNB. An eNB for a pico cell may be referred to asa pico eNB. An eNB for a femto cell may be referred to as a femto eNB ora home eNB (HeNB). In the example shown in FIG. 1, an eNB 110 a may be amacro eNB for a macro cell 102 a, an eNB 110 b may be a pico eNB for apico cell 102 b, and an eNB 110 c may be a femto eNB for a femto cell102 c. An eNB may support one or multiple (e.g., three) cells. The terms“eNB”, “base station,” and “cell” may be used interchangeably herein.

Wireless communication network 100 may also include relay stations. Arelay station is an entity that can receive a transmission of data froman upstream station (e.g., an eNB or a UE) and send a transmission ofthe data to a downstream station (e.g., a UE or an eNB). A relay stationmay also be a UE that can relay transmissions for other UEs. In theexample shown in FIG. 1, a relay (station) eNB 110 d may communicatewith macro eNB 110 a and a UE 120 d in order to facilitate communicationbetween eNB 110 a and UE 120 d. A relay station may also be referred toas a relay eNB, a relay base station, a relay, etc.

Wireless communication network 100 may be a heterogeneous network thatincludes eNBs of different types, e.g., macro eNBs, pico eNBs, femtoeNBs, relay eNBs, etc. These different types of eNBs may have differenttransmit power levels, different coverage areas, and different impact oninterference in wireless communication network 100. For example, macroeNBs may have a high transmit power level (e.g., 5 to 40 W) whereas picoeNBs, femto eNBs, and relay eNBs may have lower transmit power levels(e.g., 0.1 to 2 W).

A network controller 130 may couple to a set of eNBs and may providecoordination and control for these eNBs. Network controller 130 maycommunicate with the eNBs via a backhaul. The eNBs may also communicatewith one another, e.g., directly or indirectly via a wireless orwireline backhaul.

UEs 120 (e.g., 120 a, 120 b, 120 c) may be dispersed throughout wirelesscommunication network 100, and each UE may be stationary or mobile. A UEmay also be referred to as an access terminal, a terminal, a mobilestation (MS), a subscriber unit, a station (STA), etc. A UE may be acellular phone, a personal digital assistant (PDA), a wireless modem, awireless communication device, a handheld device, a laptop computer, acordless phone, a wireless local loop (WLL) station, a tablet, a smartphone, a netbook, a smartbook, an ultrabook, navigation devices, gamingdevices, cameras, a vehicular device, a drone, a robot/robotic device, awearable device (e.g., smart watch, smart clothing, smart wristband,smart ring, smart bracelet, smart glasses, virtual reality goggles), amedical device, a healthcare device, etc. MTC UEs include devices suchas sensors, meters, monitors, location tags, drones, trackers,robots/robotic devices, etc. UEs (e.g., MTC devices) may be implementedas Internet of Everything (IoE) or Internet of Things (IoT) (e.g.,narrowband IoT (NB-IoT)) devices.

One or more UEs 120 in the wireless communication network 100 (e.g., anLTE network) may also be low cost (LC), low data rate devices, e.g.,such as LC MTC UEs, LC eMTC UEs, etc. The LC UEs may co-exist withlegacy and/or advanced UEs in the LTE network and may have one or morecapabilities that are limited when compared to the other UEs (e.g.,non-LC UEs) in the wireless network. For example, when compared tolegacy and/or advanced UEs in the LTE network, the LC UEs may operatewith one or more of the following: a reduction in maximum bandwidth(relative to legacy UEs), a single receive radio frequency (RF) chain,reduction of peak rate, reduction of transmit power, rank 1transmission, half duplex operation, etc. As used herein, devices withlimited communication resources, such as MTC devices, eMTC devices, etc.are referred to generally as LC UEs. Similarly, legacy devices, such aslegacy and/or advanced UEs (e.g., in LTE) are referred to generally asnon-LC UEs.

FIG. 2 is a block diagram of a design of BS/eNB 110 and UE 120, whichmay be one of the BSs/eNBs 110 and one of the UEs 120, respectively, inFIG. 1. BS 110 may be equipped with T antennas 234 a through 234 t, andUE 120 may be equipped with R antennas 252 a through 252 r, where ingeneral T≥1 and R≥1.

At BS 110, a transmit processor 220 may receive data from a data source212 for one or more UEs, select one or more modulation and codingschemes (MCSs) for each UE based on channel quality indicators (CQIs)received from the UE, process (e.g., encode and modulate) the data foreach UE based on the MCS(s) selected for the UE, and provide datasymbols for all UEs. Transmit processor 220 may also process systeminformation (e.g., for semi-static resource partitioning information(SRPI), etc.) and control information (e.g., CQI requests, grants, upperlayer signaling, etc.) and provide overhead symbols and control symbols.Processor 220 may also generate reference symbols for reference signals(e.g., the common reference signal (CRS)) and synchronization signals(e.g., the primary synchronization signal (PSS) and secondarysynchronization signal (SSS)). A transmit (TX) multiple-inputmultiple-output (MIMO) processor 230 may perform spatial processing(e.g., precoding) on the data symbols, the control symbols, the overheadsymbols, and/or the reference symbols, if applicable, and may provide Toutput symbol streams to T modulators (MODs) 232 a through 232 t. EachMOD 232 may process a respective output symbol stream (e.g., for OFDM,etc.) to obtain an output sample stream. Each MOD 232 may furtherprocess (e.g., convert to analog, amplify, filter, and upconvert) theoutput sample stream to obtain a downlink signal. T downlink signalsfrom modulators 232 a through 232 t may be transmitted via T antennas234 a through 234 t, respectively.

At UE 120, antennas 252 a through 252 r may receive the downlink signalsfrom BS 110 and/or other BSs and may provide received signals todemodulators (DEMODs) 254 a through 254 r, respectively. Each DEMOD 254may condition (e.g., filter, amplify, downconvert, and digitize) itsreceived signal to obtain input samples. Each DEMOD 254 may furtherprocess the input samples (e.g., for OFDM, etc.) to obtain receivedsymbols. A MIMO detector 256 may obtain received symbols from all Rdemodulators 254 a through 254 r, perform MIMO detection on the receivedsymbols if applicable, and provide detected symbols. A receive processor258 may process (e.g., demodulate and decode) the detected symbols,provide decoded data for UE 120 to a data sink 260, and provide decodedcontrol information and system information to a controller/processor280. A channel processor may determine reference signal received power(RSRP), received signal strength indicator (RSSI), reference signalreceived quality (RSRQ), CQI, etc.

On the uplink, at UE 120, a transmit processor 264 may receive andprocess data from a data source 262 and control information (e.g., forreports comprising RSRP, RSSI, RSRQ, CQI, etc.) fromcontroller/processor 280. Processor 264 may also generate referencesymbols for one or more reference signals. The symbols from transmitprocessor 264 may be precoded by a TX MIMO processor 266 if applicable,further processed by MODs 254 a through 254 r (e.g., for SC-FDM, OFDM,etc.), and transmitted to BS 110. At BS 110, the uplink signals from UE120 and other UEs may be received by antennas 234, processed by DEMODs232, detected by a MIMO detector 236 if applicable, and furtherprocessed by a receive processor 238 to obtain decoded data and controlinformation sent by UE 120. Processor 238 may provide the decoded datato a data sink 239 and the decoded control information tocontroller/processor 240. BS 110 may include communication unit 244 andcommunicate to network controller 130 via communication unit 244.Network controller 130 may include communication unit 294,controller/processor 290, and memory 292.

Controllers/processors 240 and 280 may direct the operation at BS 110and UE 120, respectively. For example, controller/processor 240 and/orother processors and modules at BS 110 may perform or direct operationsillustrated in FIGS. 10, 13, 14, 17 and/or other processes for thetechniques described herein. Similarly, controller/processor 280 and/orother processors and modules at UE 120 may perform or direct operationsillustrated in FIGS. 11, 12, 15, 16 and/or processes for the techniquesdescribed herein. Memories 242 and 282 may store data and program codesfor BS 110 and UE 120, respectively. A scheduler 246 may schedule UEsfor data transmission on the downlink and/or uplink.

FIG. 3 shows an exemplary frame structure 300 for FDD in LTE. Thetransmission timeline for each of the downlink and uplink may bepartitioned into units of radio frames. Each radio frame may have apredetermined duration (e.g., 10 milliseconds (ms)) and may bepartitioned into 10 subframes with indices of 0 through 9. Each subframemay include two slots. Each radio frame may thus include 20 slots withindices of 0 through 19. Each slot may include L symbol periods, e.g.,seven symbol periods for a normal cyclic prefix (as shown in FIG. 2) orsix symbol periods for an extended cyclic prefix. The 2L symbol periodsin each subframe may be assigned indices of 0 through 2L−1.

In LTE, an eNB may transmit a primary synchronization signal (PSS) and asecondary synchronization signal (SSS) on the downlink in the center1.08 MHz of the system bandwidth for each cell supported by the eNB. ThePSS and SSS may be transmitted in symbol periods 6 and 5, respectively,in subframes 0 and 5 of each radio frame with the normal cyclic prefix,as shown in FIG. 3. The PSS and SSS may be used by UEs for cell searchand acquisition. The eNB may transmit a cell-specific reference signal(CRS) across the system bandwidth for each cell supported by the eNB.The CRS may be transmitted in certain symbol periods of each subframeand may be used by the UEs to perform channel estimation, channelquality measurement, and/or other functions. The eNB may also transmit aphysical broadcast channel (PBCH) in symbol periods 0 to 3 in slot 1 ofcertain radio frames. The PBCH may carry some system information. TheeNB may transmit other system information such as system informationblocks (SIBs) on a physical downlink shared channel (PDSCH) in certainsubframes. The eNB may transmit control information/data on a physicaldownlink control channel (PDCCH) in the first B symbol periods of asubframe, where B may be configurable for each subframe. The eNB maytransmit traffic data and/or other data on the PDSCH in the remainingsymbol periods of each subframe.

The PSS, SSS, CRS, and PBCH in LTE are described in 3GPP TS 36.211,entitled “Evolved Universal Terrestrial Radio Access (E-UTRA); PhysicalChannels and Modulation,” which is publicly available.

FIG. 4 shows two example subframe formats 410 and 420 for the downlinkwith a normal cyclic prefix. The available time frequency resources forthe downlink may be partitioned into resource blocks. Each resourceblock may cover 12 subcarriers in one slot and may include a number ofresource elements. Each resource element may cover one subcarrier in onesymbol period and may be used to send one modulation symbol, which maybe a real or complex value.

Subframe format 410 may be used for an eNB equipped with two antennas. ACRS may be transmitted from antennas 0 and 1 in symbol periods 0, 4, 7,and 11. A reference signal is a signal that is known a priori by atransmitter and a receiver and may also be referred to as pilot. A CRSis a reference signal that is specific for a cell, e.g., generated basedon a cell identity (ID). In FIG. 4, for a given resource element withlabel Ra, a modulation symbol may be transmitted on that resourceelement from antenna a, and no modulation symbols may be transmitted onthat resource element from other antennas. Subframe format 420 may beused for an eNB equipped with four antennas. A CRS may be transmittedfrom antennas 0 and 1 in symbol periods 0, 4, 7, and 11 and fromantennas 2 and 3 in symbol periods 1 and 8. For both subframe formats410 and 420, a CRS may be transmitted on evenly spaced subcarriers,which may be determined based on cell ID. Different eNBs may transmittheir CRSs on the same or different subcarriers, depending on their cellIDs. For both subframe formats 410 and 420, resource elements not usedfor the CRS may be used to transmit data (e.g., traffic data, controldata, and/or other data).

An interlace structure may be used for each of the downlink and uplinkfor FDD in LTE. For example, Q interlaces with indices of 0 through Q−1may be defined, where Q may be equal to 4, 6, 8, 10, or some othervalue. Each interlace may include subframes that are spaced apart by Qframes. In particular, interlace q may include subframes q, q+Q, q+2Q,etc., where q∈{0, . . . , Q−1}.

The wireless network may support hybrid automatic retransmission request(HARQ) for data transmission on the downlink and uplink. For HARQ, atransmitter (e.g., an eNB 110) may send one or more transmissions of apacket until the packet is decoded correctly by a receiver (e.g., a UE120) or some other termination condition is encountered. For synchronousHARQ, all transmissions of the packet may be sent in subframes of asingle interlace. For asynchronous HARQ, each transmission of the packetmay be sent in any subframe.

A UE may be located within the coverage of multiple eNBs. One of theseeNBs may be selected to serve the UE. The serving eNB may be selectedbased on various criteria such as received signal strength, receivedsignal quality, path loss, etc. Received signal quality may bequantified by a signal-to-interference-plus-noise ratio (SINR), or areference signal received quality (RSRQ), or some other metric. The UEmay operate in a dominant interference scenario in which the UE mayobserve high interference from one or more interfering eNBs.

As mentioned above, one or more UEs in the wireless communicationnetwork (e.g., wireless communication network 100) may be devices thathave limited communication resources, such as LC UEs, as compared toother (non-LC) devices in the wireless communication network.

In some systems, for example, in LTE Rel-13, the LC UE may be limited toa particular narrowband assignment (e.g., of no more than six resourceblocks (RBs)) within the available system bandwidth. However, the LC UEmay be able to re-tune (e.g., operate and/or camp) to differentnarrowband regions within the available system bandwidth of the LTEsystem, for example, in order to co-exist within the LTE system.

As another example of coexistence within the LTE system, LC UEs may beable to receive (with repetition) legacy physical broadcast channel(PBCH) (e.g., the LTE physical channel that, in general, carriesparameters that may be used for initial access to the cell) and supportone or more legacy physical random access channel (PRACH) formats. Forexample, the LC UE may be able to receive the legacy PBCH with one ormore additional repetitions of the PBCH across multiple subframes. Asanother example, the LC UE may be able to transmit one or morerepetitions of PRACH (e.g., with one or more PRACH formats supported) toan eNB in the LTE system. The PRACH may be used to identify the LC UE.Also, the number of repeated PRACH attempts may be configured by theeNB.

The LC UE may also be a link budget limited device and may operate indifferent modes of operation (e.g. entailing different amounts ofrepeated messages transmitted to or from the LC UE) based on its linkbudget limitation. For example, in some cases, the LC UE may operate ina normal coverage mode in which there is little to no repetition (e.g.,the amount of repetition needed for the UE to successfully receiveand/or transmit a message may be low or repetition may not even beneeded). Alternatively, in some cases, the LC UE may operate in acoverage enhancement (CE) mode in which there may be high amounts ofrepetition. For example, for a 328 bit payload, a LC UE in CE mode mayneed 150 or more repetitions of the payload in order to successfullyreceive the payload.

In some cases, e.g., also for LTE Rel-13, the LC UE may have limitedcapabilities with respect to its reception of broadcast and unicasttransmissions. For example, the maximum transport block (TB) size for abroadcast transmission received by the LC UE may be limited to 1000bits. Additionally, in some cases, the LC UE may not be able to receivemore than one unicast TB in a subframe. In some cases (e.g., for boththe CE mode and normal mode described above), the LC UE may not be ableto receive more than one broadcast TB in a subframe. Further, in somecases, the LC UE may not be able to receive both a unicast TB and abroadcast TB in a subframe.

For MTC, LC UEs that co-exist in the LTE system may also support newmessages for certain procedures, such as paging, random accessprocedure, etc. (e.g., as opposed to conventional messages used in LTEfor these procedures). In other words, these new messages for paging,random access procedure, etc. may be separate from the messages used forsimilar procedures associated with non-LC UEs. For example, as comparedto conventional paging messages used in LTE, LC UEs may be able tomonitor and/or receive paging messages that non-LC UEs may not be ableto monitor and/or receive. Similarly, as compared to conventional randomaccess response (RAR) messages used in a conventional random accessprocedure, LC UEs may be able to receive RAR messages that also may notbe able to be received by non-LC UEs. The new paging and RAR messagesassociated with LC UEs may also be repeated one or more times (e.g.,“bundled”). In addition, different numbers of repetitions (e.g.,different bundling sizes) for the new messages may be supported.

Example Narrowband Coexistence within a Wideband System

As mentioned above, narrowband (e.g., MTC or NB-IoT) operation may besupported in the wireless communication network (e.g., in coexistencewith LTE or some other RAT). FIGS. 5A and 5B, for example, illustrate anexample of how LC UEs in MTC operation may co-exist within a widebandsystem, such as LTE.

As illustrated in the example frame structure of FIG. 5A, subframes 510associated with MTC and/or eMTC operation may be time divisionmultiplexed (TDM) with regular subframes 520 associated with LTE (orsome other RAT).

Additionally or alternatively, as illustrated in the example framestructure of FIG. 5B, one or more narrowband regions 560, 562 used by LCUEs in MTC may be frequency division multiplexed within the widerbandwidth 550 supported by LTE. Multiple narrowband regions, with eachnarrowband region spanning a bandwidth that is no greater than a totalof 6 RBs, may be supported for MTC and/or eMTC operation. In some cases,each LC UE in MTC operation may operate within one narrowband region(e.g., at 1.4 MHz or 6 RBs) at a time. However, LC UEs in MTC operation,at any given time, may re-tune to other narrowband regions in the widersystem bandwidth. In some examples, multiple LC UEs may be served by thesame narrowband region. In other examples, multiple LC UEs may be servedby different narrowband regions (e.g., with each narrowband regionspanning 6 RBs). In yet other examples, different combinations of LC UEsmay be served by one or more same narrowband regions and/or one or moredifferent narrowband regions.

The LC UEs may operate (e.g., monitor/receive/transmit) within thenarrowband regions for various different operations. For example, asshown in FIG. 5B, a first narrowband region 560 (e.g., spanning no morethan 6 RBs of the wideband data) of a subframe 552 may be monitored byone or more LC UEs for either a PSS, SSS, PBCH, MTC signaling, or pagingtransmission from a BS in the wireless communication network. As alsoshown in FIG. 5B, a second narrowband region 562 (e.g., also spanning nomore than 6 RBs of the wideband data) of a subframe 554 may be used byLC UEs to transmit a RACH or data previously configured in signalingreceived from a BS. In some cases, the second narrowband region may beutilized by the same LC UEs that utilized the first narrowband region(e.g., the LC UEs may have re-tuned to the second narrowband region totransmit after monitoring in the first narrowband region). In some cases(although not shown), the second narrowband region may be utilized bydifferent LC UEs than the LC UEs that utilized the first narrowbandregion.

Although the examples described herein assume a narrowband of 6 RBs,those skilled in the art will recognize that the techniques presentedherein may also be applied to different sizes of narrowband regions.

Example Narrowband Management for MTC

As mentioned above, in certain systems, e.g., such as LTE Rel-12,narrowband operation for MTC (e.g., eMTC) may be supported. A cellsupporting narrowband operation for MTC may have different systembandwidths for downlink (DL) and uplink (UL) operations. A cell havingdifferent DL and UL system bandwidths (SBs) may organize the DL systembandwidth into narrowband regions in a manner different than the mannerused to organize the UL system bandwidth into narrowband regions.Accordingly, aspects of the present disclosure provide techniques fororganizing a DL system bandwidth and an UL system bandwidth intonarrowband regions.

A cell supporting narrowband operation for MTC and legacy UEs mayreceive legacy PUCCH transmissions from the legacy UEs. Legacy PUCCHtransmissions may be transmitted at either or both edges of a UL systembandwidth of a cell. Accordingly, aspects of the present disclosureprovide techniques to reserve transmission resources included in an ULnarrowband region for use by legacy PUCCH transmissions. Similarreservations may also be applied to a DL narrowband region for use byother legacy DL signals or channels.

A cell supporting narrowband operations for MTC may also supporttransmission of sounding reference signals (SRS). The current minimumdefined bandwidth for transmission of SRS is four RBs. However, asmentioned above, the bandwidth of narrowband regions is six RBs. Thefact that six RBs are not divisible by four RBs presents challenges inmanaging SRS transmissions using four RBs in six-RB based narrowbandoperations. Accordingly, aspects of the present disclosure providetechniques for assigning transmission resources for transmission of SRSin a cell supporting narrowband operations (e.g., for MTC).

A cell operating with FDD may have a DL system bandwidth that is of adifferent size than the UL system bandwidth of the cell. For example, acell may perform DL operations in a system bandwidth of ten MHz and ULoperations in a five MHz system bandwidth. To support MTC operations andMTC UEs, the cell may organize the DL system bandwidth and the UL systembandwidth into narrowband regions, or narrowband regions. An eNB orother BS controlling the cell may assign a DL narrowband region to a MTCUE for the MTC UE to monitor for signals from the eNB. Similarly, theeNB (or other BS) may assign a UL narrowband region to the MTC UE forthe MTC to use when transmitting UL signals. In the example, the cellmay organize the DL system bandwidth into eight DL narrowband regionswhile organizing the UL system bandwidth into four UL narrowbandregions.

When a BS (e.g., an eNB or a cell) supports MTC UEs with the DL systembandwidth and UL system bandwidth of the cell organized into narrowbandregions, the BS may establish a mapping between DL narrowband regionsand UL narrowband regions, so that assigning a DL narrowband region toan MTC UE implies an assignment of a UL narrowband region to that MTCUE. Having a mapping allows the BS to simplify scheduling of resourcesin the cell, e.g., the BS can expect ACK/NAKs for transmissions on a DLnarrowband region to an MTC UE on the corresponding UL narrowbandregion. Likewise, an MTC UE monitors for DL transmissions on theassigned DL narrowband region for the MTC UE and responds withtransmissions on the corresponding UL narrowband region.

According to aspects of the present disclosure, a technique for mappingUL and DL narrowband regions by a BS is provided. A BS may determine aminimum size of the UL system bandwidth and the DL system bandwidthsupported by the BS, determine a number of narrowband regions that canbe organized in the determined size, and then organize both the DLsystem bandwidth and the UL system bandwidth in that number ofnarrowband regions. The BS may then map each DL narrowband region to oneUL narrowband region. For example, a cell may perform DL operations in asystem bandwidth of ten MHz and UL operations in a five MHz systembandwidth. In the example, the BS may determine that the minimum size ofthe UL system bandwidth and the DL system bandwidth is five MHz, andthen determine that the BS can organize four narrowband regions in afive MHz system bandwidth. Still in the example, the BS may thenorganize four DL narrowband regions in the DL system bandwidth and fourUL narrowband regions in the UL system bandwidth, and map each DLnarrowband region to one UL narrowband region.

FIG. 6 illustrates an exemplary mapping 600 of DL narrowband regions toUL narrowband regions, as described above. Such a mapping may beemployed by eNB 110 a in FIG. 1. While FIG. 6 shows the DL systembandwidth 610 and the UL system bandwidth 650 as apparently in the samefrequency ranges, the DL system bandwidth and the UL system bandwidthare in different frequency ranges in a cell using FDD. DL systembandwidth 610 is ten MHz or fifty RBs wide, and UL system bandwidth 650is five MHz or twenty-five RBs wide. A BS supporting MTC UEs whileoperating DL system bandwidth 610 and UL system bandwidth 650 maydetermine that the UL system bandwidth 650 is smaller than DL systembandwidth 610 (the 5 MHz size of UL system bandwidth 650 is the minimumsize of the UL system bandwidth 650 and the DL system bandwidth 610).The BS may then determine that the BS can organize four narrowbandregions 652, 654, 656, and 658 from the UL system bandwidth 650. The BSmay then determine to organize four narrowband regions from the DLsystem bandwidth, and organize DL narrowband regions 612, 614, 616, and618 from the DL system bandwidth. The BS may then map DL narrowbandregion 612 to UL narrowband region 652, DL narrowband region 614 to ULnarrowband region 654, DL narrowband region 616 to UL narrowband region656, and DL narrowband region 618 to UL narrowband region 658.

As mentioned above, LC MTC UEs were introduced in LTE Rel-12. Additionalenhancements may be made in LTE Release 13 (Rel-13) to support MTCoperations. For example, MTC UEs may be able to operate (e.g., monitor,transmit, and receive) in a narrowband region of 1.4 MHz or six RBswithin wider system bandwidths (e.g., 1.4 MHz, 3 MHz, 5 MHz, 10 MHz, 15MHz, 20 MHz). As a second example, base stations and MTC UEs may supportcoverage enhancements (CE) of up to 20 dB by some techniques, forexample bundling. Coverage enhancement may also be referred to ascoverage extension and range extension.

When a UE needs to connect with a cell to which the UE is not currentlyconnected, the UE and the cell engage in an exchange of messagesreferred to as a random access channel (RACH) procedure. In a RACHprocedure, a UE transmits a physical random access channel (PRACH)signal (sometimes referred to as Msg1 of a RACH procedure) in a set oftransmission resources reserved for PRACH signals, then the cellresponds to the PRACH signal with a random access response (RAR) message(sometimes referred to as Msg2 of a RACH procedure) carried on thedownlink shared channel (DL-SCH). The UE responds to the RAR messagewith an RRC connection request message (sometimes referred to as Msg3 ofa RACH procedure), and the cell responds with a contention resolutionmessage (sometimes referred to as Msg4 of a RACH procedure). The UE isthen connected with the cell.

In current (e.g., LTE Rel-12) wireless technologies, a PRACH signaltransmitted by an MTC device comprises one group of 4 symbols in asingle tone and using 2 hopping values.

As will be described in further details below, according to certainaspects of the present disclosure, a PRACH signal may be utilized in anuplink-based positioning procedure.

Narrowband Positioning Signal Design and Procedures

As described above, systems which deploy narrowband devices, such as MTCand NB-IoT devices, are challenged when performing positioningprocedures. These challenges may arise from the limited frequencydimension (e.g., 1 RB system bandwidth of 200 kHz), multi-user capacity,and deep coverage in certain device deployments, and the possibility ofsupporting different coverage enhancement levels. In some cases,coverage enhancement of as much as 20 dB may be desirable, which may beachieved through long bundling (e.g., over multiple subframes, whichimpacts limited time resources). In addition, such systems may have arelatively large cell radius (e.g., as much as 35 km), resulting in longtransmission delays (e.g., by as much as 200 μs).

Aspects of the present disclosure provide various mechanisms forpositioning in systems that deploy narrowband devices. As will bedescribed in greater detail below, such mechanisms may include downlinkbased positioning procedures (based on DL positioning reference signalsor DL PRS), uplink based positioning procedures (based on UL PRS), andhybrid approaches (e.g., based on a combination of DL PRS and UL PRS).

In general, PRS signals may be transmitted within pre-defined bandwidthand according to a set of configuration parameters such as subframeoffset, periodicity, and duration. Further, each cell of a network mayapply a different muting pattern (defining times in which the cell doesnot transmit PRS) in an effort to avoid interference with PRStransmitted from other cells. PRS may be transmitted at pre-definedsubframes and repeated (e.g., in several consecutive subframes that maybe referred to as “positioning occasions”). The PRS itself may be basedon any suitable known sequence (e.g., a Zadoff-Chu sequence). PRS fromdifferent cells may be multiplexed in the code domain (each celltransmitting a different (orthogonal) PRS sequence), in the frequencydomain (e.g., at different frequency offsets), and/or in the time domain(e.g., using time-based blanking).

According to a DL-based positioning approach, one or more base stationsmay transmit PRS in one or more narrowband regions of a wider systembandwidth. A wireless node (e.g., a UE) may monitor for such DL PRS andperform timing and/or location estimation based on the DL PRS. The UEmay estimate the location of the UE by obtaining positions of BSs fromwhich the UE receives DL PRS and performing a trilateration procedurebased on the positions of the BSs and the timing of the DL PRS.Additionally or alternatively, the UE may supply identifiers of BSs fromwhich the UE receives DL PRS and timing information and/or thoseparameters to a location services (LCS) server, which may performtrilateration to estimate the location of the UE.

As illustrated in FIG. 7, in some cases PRS 702 may be staggered (e.g.,across symbols within a subframe and/or across PRS tones). In addition,PRS may be repeated (e.g., across multiple symbols within a samesubframe or across multiple subframes). Staggering across multiple tonesmay provide frequency diversity and be suitable for wide-band operationinvolving IDFT based receivers. The PRS 702 may be located to avoid CRS704 and resources 706 (e.g., the first three symbols) used for commandsignaling (e.g., PCFICH/PHICH/PDCCH).

Repeating and/or staggering PRS within a single tone, as shown in FIG.8, may allow for coherent combining of the PRS (providing additionalgain). And the combination of the PRS may be done without estimating afrequency offset. The PRS may hop to a different PRS tone (e.g., a tonewith a different tone index), for example, across time slots or acrosssubframes. An example of PRS hopping from one tone to another toneacross subframes may be seen by comparing the PRS at 810 with the PRS at820.

Repeating and/or staggering PRS within a single tone may be particularlysuitable for positioning procedures involving devices in deep coverageand/or phase-offset based receivers. For in-band deployment (e.g., wherethe narrowband regions are within system bandwidth used for wide-bandcommunications), the cyclic prefix (CP) of the PRS may be the same asthe CP used for wide-band communications (e.g., normal CP or extendedCP). In some cases, CP may be limited by cell size (e.g., a cell of agiven size requires a minimum CP for accurate decoding of signals withinthe cell).

For UL-PRS, in some cases, a physical random access channel (PRACH) likesignal may be transmitted (e.g., within a single tone with 2 hoppingvalues). In such cases, a single PRACH-like PRS transmission may beintended to reach multiple BSs. Because a UE is normally aligned to DLtiming of a serving cell, the UE may transmit PRS based on this DLtiming. PRS transmitted by a UE based DL timing of a serving cell of theUE might lead to a negative delay for the PRS in a base station of oneor more neighboring cells (e.g., if the UE is closer to the BS of theneighboring cell than the BS of the serving cell, PRS from the UE willarrive early at the BS of the neighboring cell and appear to have anegative delay). One approach to account for this is to have BSs monitorto detect PRS having negative delay. Another approach is for a UE todelay PRS transmission by a certain amount, wherein the amount isselected so all desired BSs will experience positive delays whenreceiving the PRS from the UE and thus eliminating the need to check forPRS having negative delay.

In some cases, a PRACH-like signal used for positioning may havedifferent parameters from a normal PRACH (e.g., CP length, Frequencyband, tones, time, hopping values). In some cases, a BS (e.g., an eNB)may set 1 bit in a PDCCH scheduling a PRACH by a UE (e.g., a scheduledor commanded PRACH) in order to indicate to the UE that the PRACH is tobe used for a positioning or PRS procedure, as opposed to a PRACHprocedure. A UE may then detect this bit as set and act accordingly(e.g., delaying the UL transmission if used for PRS).

As illustrated in FIG. 9, in some cases UL PRS may be transmitted on asingle tone with a fixed hopping value. In some cases, a different typeof signal may be used for PRS, e.g., with different parameters from thePRACH-like signal described above (e.g., different CP length, differenttone spacing, different number of hopping values or different hoppingvalue). In some cases, a random hopping value may be used in addition toa fixed hopping value.

In some cases, one or more aspects of UL and/or DL PRS procedures may becell dependent. For example, for a small cell size with synchronizedeNBs, the distance to the most distant eNB may be within a CP for normaldata, and PRS may be transmitted using the same CP length as the CP fornormal data. As another example, a UE may first perform cell access,obtain a PRS configuration (for that cell) and at the same time, receivePRS from multiple cells, and perform timing and/or location estimationfor the multiple cells.

According to aspects of the present disclosure, if a UE is in aconnected mode, the UE may receive scheduling (e.g., an UL grant) fortransmitting an UL PRS. In some cases, the UE may transmit UL PRS as asingle tone with one hopping value (e.g., as illustrated in FIG. 9) tomultiple cells. In such cases, the round-trip delay from the UE to themost distant BS (e.g., eNB) serving one of the multiple cells should bewithin the length of a CP of the UL PRS. In some cases, one hoppingvalue may be determined based on cell size and/or CP size. In somecases, multiple BSs (e.g., eNBs) may estimate timing and/or locationsimultaneously based on UL PRS.

On the other hand, for large cell sizes and/or asynchronous cells (whereBSs are not synchronized), a DL-based PRS procedure may be performed instages. For example, in a first stage, the UE may acquire each cellbased on PSS/SSS/PBCH. The UE may acquire PRS configuration and/or otherinformation from each cell when the UE has acquired that cell. In asecond stage, timing estimation may be performed by the UE based on DLPRS and using information (e.g., PRS configuration, timing information),if any, acquired from the cells, as described above. Of course, othercell signals having different CP lengths may cause inter-cellinterference.

In some cases, an UL-based PRS procedure may also be performed inmultiple stages. For example, in a first stage, a UE may send UL PRS asa single transmission to multiple BSs (if the cells of the BSs are smalland/or synchronized) or multiple PRS transmissions, each to one or a fewBSs, for BSs serving large and/or asynchronous cells. The UL PRS may betransmitted on a single tone with a fixed hopping value and/or using arandom hopping value, as described above with reference to FIGS. 8-9. Ina second stage, each BSs may perform timing estimation, based on the ULPRS directed to that BS.

In a hybrid PRS procedure, a combination of UL PRS and DL PRS may beused. For example, in a “DL-UL-DL” hybrid approach, a UE may get DL PRSfrom a serving cell and UL PRS configuration(s) for multiple cells. TheUE may receive eNB scheduling for UL PRS and transmit UL PRS based onthe UL PRS configuration(s) and as described above with reference toFIGS. 8-9. eNBs may then perform a rough DL timing offset estimationbetween eNBs. The UE may then receive one or more DL timing adjustmentscorresponding to one or more of the eNBs. For each cell, the UE mayadjust DL timing (e.g., by applying the DL timing adjustments) and usethe adjusted DL timing to perform a DL based PRS procedure.

In a “DL-DL-UL” hybrid approach, a UE may again get DL PRS from aserving cell and UL PRS configuration(s) for multiple neighbor cells.The UE may then use PSS/SSS to get DL timing offset estimates for BSsserving the multiple neighbor cells. For each neighbor cell, the UE maydetermine UL timing adjustments (TA) adjustments based on the DL timingoffset for each neighbor cell. The UE may then transmit UL PRS based onthe UL TA adjustments for each neighbor cell.

In some cases, PRS bandwidth may be expanded with hopping, for example,when there are multiple RBs available. In such cases, for DL-based PRS,the eNB may transmit PRS signals over multiple RBs (e.g., with the UEreceiving PRS in one RB in each time period). The UE may retune areceiver to receive the PRS in the different RBs and then estimate aphase offset resulting from the retuning and compensate for the phaseoffset. The UE may concatenate the received PRS RBs together toeffectively process a wider bandwidth of PRS signals. The UE may thenuse these enhanced (e.g., concatenated) PRS signals to estimate timing.

For UL-based PRS, a UE may transmit UL PRS at different tone and/or RBlocations at different times (e.g., different symbols within a samesubframe or across multiple subframes). In this case, an eNB mayestimate a phase offset due to retuning (e.g., to receive the PRS in thedifferent tone and/or RB locations) and compensate for the phase offset.In such cases, the eNB may concatenate multiple tones and/or RBstogether to effectively process a wider bandwidth of PRS signals. Insome cases, consecutive PRS subframes may be longer than legacy, mayhave a smaller periodicity, and/or may have more PRS subframes perperiod.

In addition, different eNBs may also use different RBs when transmittingDL PRS to avoid or reduce muting. In some cases, eNBs may reserve someRBs just for positioning (e.g. for transmission of PRS), with less or nonormal data (e.g., PDSCH) scheduled for those RBs.

FIGS. 10-17 illustrate various operations for DL-based and UL-based PRSprocedures from the base station (e.g., eNB) and wireless node (e.g.,UE) perspectives.

For example, FIG. 10 illustrates example operations 1000 fordownlink-based narrowband PRS that may be performed by a BS, inaccordance with certain aspects of the present disclosure. Theoperations 1000 begin, at 1002, by determining resources within anarrowband region of wider system bandwidth for transmitting downlinkpositioning reference signals (PRS) to one or more wireless nodes. At1004, the BS transmits the downlink PRS using the determined resources,wherein the transmitting comprises transmitting tones of the PRSrepeated across at least one of: multiple symbols within a samesubframe, or multiple consecutive subframes.

FIG. 11 illustrates example operations 1100 for downlink-basednarrowband PRS that may be performed by a wireless node and may beconsidered complementary to operations 1000 of FIG. 10. For example,operations 1100 may be performed by a UE monitoring the DL PRStransmitted in FIG. 10. Operations 1100 begin, at 1102, by monitoringfor positioning reference signals (PRS) transmitted, from one or morebase stations (BSs), within a narrowband region of wider systembandwidth, wherein tones of the PRS are repeated across at least one of:multiple symbols within a same subframe, or multiple consecutivesubframes. At 1104, the wireless node estimates timing from the one ormore base stations based on the PRS.

FIG. 12 illustrates example operations 1200 for uplink-based narrowbandPRS that may be performed by a wireless node, in accordance with certainaspects of the present disclosure. The operations 1200 begin, at 1202,by determining resources within a narrowband region of wider systembandwidth for transmitting positioning reference signals (PRS) to one ormore base stations. At 1204, the wireless node transmits the PRS usingthe determined resources.

FIG. 13 illustrates example operations 1300 for uplink-based narrowbandPRS that may be performed by a BS and may be considered complementary tooperations 1200 of FIG. 12. The operations 1300 begin, at 1302, bymonitoring for first positioning reference signals (PRS) transmitted,from a wireless node, within a narrowband region of a wider systembandwidth. At 1304, the BS estimates timing from the wireless node basedon the first PRS.

FIG. 14 illustrates example operations 1400 for downlink-based PRSacross multiple narrowbands that may be performed by a BS, in accordancewith certain aspects of the present disclosure. The operations 1400begin, at 1402, by determining resources in a plurality of narrowbandregions within wider system bandwidth for transmitting positioningreference signals (PRS) to at least one wireless node. At 1402, the BStransmits the PRS using the determined resources.

FIG. 15 illustrates example operations 1500 for downlink-basednarrowband PRS across multiple narrowbands that may be performed by awireless node and may be considered complementary to operations 1400 ofFIG. 14. The operations 1500 begin, at 1502, by monitoring forpositioning reference signals (PRS) transmitted, from one or more basestations, across a plurality of narrowband regions within a wider systembandwidth, wherein tones of the PRS are repeated across at least one of:multiple symbols within a same subframe, or multiple consecutivesubframes. At 1504, the wireless node estimates at least one of downlinktiming or relative location of the wireless node based on the PRS.

FIG. 16 illustrates example operations 1600 for uplink-based narrowbandPRS across multiple narrowbands that may be performed by a wirelessnode, in accordance with certain aspects of the present disclosure. Theoperations 1600 begin, at 1602, by determining resources in a pluralityof narrowband regions within wider system bandwidth for transmittingpositioning reference signals (PRS) to one or more base stations. At1604, the wireless node transmits the PRS using the determinedresources.

FIG. 17 illustrates example operations 1700 for uplink-based narrowbandPRS across multiple narrowbands that may be performed by a BS and maybecomplementary to operations 1600 of FIG. 16, in accordance with certainaspects of the present disclosure. The operations 1700 begin, at 1702,by monitoring for positioning reference signals (PRS) transmitted, froma wireless node, across a plurality of narrowband regions within a widersystem bandwidth. At 1704, the BS estimates at least one of uplinktiming or relative location of the wireless node based on the PRS.

As described above, the DL-based and UL-based PRS techniques presentedherein may help facilitate positioning procedures in systems deployingnarrowband devices, such as NB-IoT devices.

As used herein, the term “or” is intended to mean an inclusive “or”rather than an exclusive “or.” That is, unless specified otherwise, orclear from the context, the phrase, for example, “X employs A or B” isintended to mean any of the natural inclusive permutations. That is, forexample the phrase “X employs A or B” is satisfied by any of thefollowing instances: X employs A; X employs B; or X employs both A andB. As used herein, reference to an element in the singular is notintended to mean “one and only one” unless specifically so stated, butrather “one or more.” For example, the articles “a” and “an” as used inthis application and the appended claims should generally be construedto mean “one or more” unless specified otherwise or clear from thecontext to be directed to a singular form. Unless specifically statedotherwise, the term “some” refers to one or more. As used herein, aphrase referring to “at least one of” a list of items refers to anycombination of those items, including single members. As an example, “atleast one of: a, b, or c” is intended to cover a, b, c, a-b, a-c, b-c,and a-b-c, as well as any combination with multiples of the same element(e.g., a-a, a-a-a, a-a-b, a-a-c, a-b-b, a-c-c, b-b, b-b-b, b-b-c, c-c,and c-c-c or any other ordering of a, b, and c).

The steps of a method or algorithm described in connection with thedisclosure herein may be embodied directly in hardware, in a softwaremodule executed by a processor, or in a combination of the two. Softwareshall be construed broadly to mean instructions, data, code, or anycombination thereof, whether referred to as software, firmware,middleware, code, microcode, hardware description language, machinelanguage, or otherwise. A software module may reside in RAM memory,flash memory, ROM memory, EPROM memory, EEPROM memory, PCM (phase changememory), registers, hard disk, a removable disk, a CD-ROM or any otherform of storage medium known in the art. An exemplary storage medium iscoupled to the processor such that the processor can read informationfrom, and/or write information to, the storage medium. In thealternative, the storage medium may be integral to the processor. Theprocessor and the storage medium may reside in an ASIC. The ASIC mayreside in a user terminal. In the alternative, the processor and thestorage medium may reside as discrete components in a user terminal.Generally, where there are operations illustrated in Figures, thoseoperations may have corresponding counterpart means-plus-functioncomponents with similar numbering. For example, operations 1000-1700,shown in FIGS. 10-17, have corresponding means-plus-function components1000A-1700A, shown in FIGS. 10A-17A.

In one or more exemplary designs, the functions described may beimplemented in hardware, software or combinations thereof. Ifimplemented in software, the functions may be stored on or transmittedover as one or more instructions or code on a computer-readable medium.Computer-readable media includes both computer storage media andcommunication media including any medium that facilitates transfer of acomputer program from one place to another. A storage media may be anyavailable media that can be accessed by a general purpose or specialpurpose computer. By way of example, and not limitation, suchcomputer-readable media can comprise RAM, ROM, EEPROM, CD-ROM or otheroptical disk storage, magnetic disk storage or other magnetic storagedevices, or any other medium that can be used to carry or store desiredprogram code means in the form of instructions or data structures andthat can be accessed by a general-purpose or special-purpose computer,or a general-purpose or special-purpose processor. Also, any connectionis properly termed a computer-readable medium. For example, if thesoftware is transmitted from a website, server, or other remote sourceusing a coaxial cable, fiber optic cable, twisted pair, digitalsubscriber line (DSL), or wireless technologies such as infrared, radio,and microwave, then the coaxial cable, fiber optic cable, twisted pair,DSL, or wireless technologies such as infrared, radio, and microwave areincluded in the definition of medium. Disk and disc, as used herein,includes compact disc (CD), laser disc, optical disc, digital versatiledisc (DVD), floppy disk and Blu-ray disc where disks usually reproducedata magnetically, while discs reproduce data optically with lasers.Combinations of the above should also be included within the scope ofcomputer-readable media.

The previous description of the disclosure is provided to enable anyperson skilled in the art to make or use the disclosure. Variousmodifications to the disclosure will be readily apparent to thoseskilled in the art, and the generic principles defined herein may beapplied to other variations without departing from the spirit or scopeof the disclosure. Thus, the disclosure is not intended to be limited tothe examples and designs described herein, but is to be accorded thewidest scope consistent with the principles and novel features disclosedherein.

What is claimed is:
 1. A method for wireless communications performed bya wireless node, comprising: monitoring for one or more positioningreference signals (PRSs) transmitted, from one or more base stations(BSs), within a narrowband region of a wider system bandwidth, whereintones of the one or more PRSs are repeated across at least one of:multiple symbols within a same subframe, or multiple consecutivesubframes; and estimating timing from the one or more base stationsbased on at least one of the one or more PRSs; wherein each of the oneor more PRSs is repeated across a set of the multiple symbols within thesame subframe or another subframe.
 2. The method of claim 1, furthercomprising providing feedback generated based on the estimated timing.3. The method of claim 2, wherein the feedback comprises at least oneof: a parameter indicating the estimated timing, an estimated distancefrom one or more of the base stations, or a location of the wirelessnode.
 4. The method of claim 1, wherein the PRSs or other PRSstransmitted from each BS are transmitted across multiple narrowbandregions.
 5. The method of claim 1, wherein one or more PRSs from each BSare transmitted within the narrowband region.
 6. The method of claim 5,wherein one or more PRSs from each BS are repeated within the narrowbandregion.
 7. The method of claim 1, wherein the tones or other tones, usedto transmit the PRSs or other PRSs in different subframes, are at leastone of staggered or hopped in tone index.
 8. The method of claim 1,wherein each positioning reference signal of the one or more PRSs isrepeated across multiple subframes.
 9. The method of claim 1, whereinthe one or more PRSs are transmitted with a same cyclic prefix (CP) asdownlink transmissions that are transmitted using a portion of thesystem bandwidth larger than the narrowband portion of the systembandwidth.
 10. The method of claim 1, further comprising: receiving aPRS configuration; and monitoring for the one or more PRSs according tothe PRS configuration.
 11. The method of claim 1, wherein the one ormore PRSs are transmitted from multiple cells.
 12. The method of claim1, wherein the monitoring for the one or more PRSs comprises monitoringfor the one or more PRSs from a base station, of the one or more basestations, only after performing a cell acquisition procedure with thatbase station.
 13. The method of claim 1, further comprising: estimatinga downlink timing offset based on the monitored one or more PRSs; andtransmitting an uplink PRS for one or more of the base stations to useto estimate an uplink timing offset.
 14. A method for wirelesscommunications performed by a wireless node, comprising: determining,for a given subframe, a narrowband region of a wider system bandwidth tomonitor for one or more positioning reference signals (PRSs) based on ahopping pattern; monitoring for the one or more PRSs transmitted, fromone or more base stations (BSs), within the narrowband region, whereineach of the one or more PRSs from each BS is transmitted within thenarrowband region, wherein the one or more PRSs from each BS arerepeated within the narrowband region, and wherein tones of the one ormore PRSs are repeated across at least one of: multiple symbols within asame subframe; or multiple consecutive subframes; and estimating timingfrom the one or more base stations based on at least one of the one ormore PRSs.
 15. A method for wireless communications performed by awireless node, comprising: monitoring for one or more positioningreference signals (PRSs) transmitted, from one or more base stations(BSs), within a narrowband region of a wider system bandwidth, whereintones of the one or more PRSs are repeated across at least one of:multiple symbols within a same subframe; or multiple consecutivesubframes; estimating timing from the one or more base stations based onat least one of the one or more PRSs; estimating a downlink timingoffset based on the monitored one or more PRSs, wherein the downlinktiming offset is estimated from a serving BS; transmitting an uplink PRSfor one or more of the base stations to use to estimate an uplink timingoffset; and applying the downlink timing offset to monitor for one ormore other PRSs transmitted from the one or more base stations, otherthan the serving BS.
 16. A method for wireless communications performedby a base station, comprising: determining resources within a narrowbandregion of a wider system bandwidth for transmitting one or more downlinkpositioning reference signals (PRSs) to one or more wireless nodes,wherein determining the resources comprises determining the resourcesfor the one or more downlink PRSs to be repeated within the narrowbandregion; and transmitting the one or more downlink PRSs using thedetermined resources, wherein the transmitting comprises transmittingtones of the one or more downlink PRSs repeated across at least one of:multiple symbols within a same subframe, or multiple consecutivesubframes; wherein each of the one or more downlink PRSs is repeatedacross a set of the multiple symbols within the same subframe or anothersubframe.
 17. The method of claim 16, wherein the determining comprisesselecting, based on a hopping pattern, different narrowband regions fordifferent times within a same subframe.
 18. The method of claim 16,wherein the determining comprises selecting, based on a hopping pattern,different narrowband regions for different subframes.
 19. The method ofclaim 16, wherein the determining comprises selecting, based on ahopping pattern, a different single tone for transmitting the one ormore downlink PRSs to different wireless nodes.
 20. An apparatus forwireless communications, comprising: a processor; memory coupled withthe processor; and instructions stored in the memory and operable, whenexecuted by the processor, to cause the apparatus to: monitor for one ormore positioning reference signals (PRSs) transmitted, from one or morebase stations (BSs), within a narrowband region of a wider systembandwidth, wherein tones of the one or more PRSs are repeated across atleast one of: multiple symbols within a same subframe, or multipleconsecutive subframes; and estimate timing from the one or more basestations based on at least one of the one or more PRSs; wherein each ofthe one or more PRSs is repeated across a set of the multiple symbolswithin the same subframe or another subframe and wherein theinstructions cause the processor to monitor for the one or more PRSs bymonitoring across the sets of the multiple symbols.
 21. The apparatus ofclaim 20, wherein the instructions further cause the apparatus toprovide feedback generated based on the estimated timing.
 22. Theapparatus of claim 21, wherein the feedback comprises at least one of: aparameter indicating the estimated timing, an estimated distance fromone or more of the base stations, or a location of the apparatus. 23.The apparatus of claim 20, wherein the PRSs or other PRSs transmittedfrom each BS are transmitted across multiple narrowband regions and theinstructions cause the apparatus to monitor for the PRS by monitoringfor each of the PRSs or the other PRSs across the multiple narrowbandregions.
 24. The apparatus of claim 20, wherein the PRS from each BS aretransmitted within the narrowband region and the instructions cause theapparatus to monitor for the PRS by monitoring for each of the PRS fromeach BS within the narrowband region.
 25. The apparatus of claim 24,wherein PRS from each BS are repeated within the narrowband region andthe instructions cause the apparatus to monitor for the PRS bymonitoring for the repeated PRS from each BS within the narrowbandregion.
 26. The apparatus of claim 20, wherein the tones or other tones,used to transmit the PRSs or other PRSs in different subframes, are atleast one of staggered or hopped in tone index and the instructionscause the apparatus to monitor for the PRSs by monitoring tones instaggered or hopped in the tone indices.
 27. The apparatus of claim 20,wherein each positioning reference signal of the one or more PRSs isrepeated across multiple subframes and the instructions cause theapparatus to monitor for the one or more PRSs by monitoring for the oneor more PRSs across multiple subframes.
 28. The apparatus of claim 20,wherein the instructions further cause the apparatus to: determine, fora given subframe, the narrowband region to monitor for the one or morePRSs based on a hopping pattern.
 29. The apparatus of claim 20, whereinthe one or more PRSs are transmitted with a same cyclic prefix (CP) asdownlink transmissions that are transmitted using a portion of thesystem bandwidth larger than the narrowband portion of the systembandwidth, and the instructions cause the apparatus to monitor for theone or more PRSs by monitoring for the one or more PRSs based on the CP.30. The apparatus of claim 20, wherein the instructions further causethe apparatus to: receive a PRS configuration, wherein the instructionscause the apparatus to monitor for the one or more PRSs according to thePRS configuration.
 31. The apparatus of claim 20, wherein the PRSs aretransmitted from multiple cells and the instructions cause the apparatusto monitor for the PRSs from the multiple cells.
 32. The apparatus ofclaim 20, wherein the instructions cause the apparatus to: perform acell acquisition procedure with a BS, of the one or more BSs; andmonitor for the one or more PRSs by monitoring for the one or more PRSsfrom the BS only after performing the cell acquisition procedure withthe BS.
 33. The apparatus of claim 20, wherein the instructions furthercause the apparatus to: estimate a downlink timing offset based on themonitored one or more PRSs; and transmit an uplink PRS for one or moreof the base stations to use to estimate an uplink timing offset.
 34. Theapparatus of claim 33, wherein the instructions cause the apparatus to:estimate the downlink timing offset from a serving BS; and apply thedownlink timing offset to monitor for one or more other PRSs transmittedfrom one or more base stations other than the serving BS.
 35. Anapparatus for wireless communications, comprising: a processor; memorycoupled with the processor; and instructions stored in the memory andoperable, when executed by the processor, to cause the apparatus to:determine resources within a narrowband region of a wider systembandwidth for transmitting one or more downlink positioning referencesignals (PRSs) to one or more wireless nodes, wherein the instructionscause the apparatus to determine the resources by causing the apparatusto determine the resources for the one or more downlink PRSs to berepeated within the narrowband region; and transmit the one or moredownlink PRSs using the determined resources, wherein the instructionscause the apparatus to transmit by causing the apparatus to transmittones of the one or more downlink PRSs repeated across at least one of:multiple symbols within a same subframe, or multiple consecutivesubframes; wherein each of the one or more downlink PRSs is repeatedacross a set of the multiple symbols within the same subframe or anothersubframe.
 36. The apparatus of claim 35, wherein the instructions causethe apparatus to determine the resources by causing the apparatus toselect, based on a hopping pattern, different narrowband regions fordifferent times within a same subframe.
 37. The apparatus of claim 35,wherein the instructions cause the apparatus to determine the resourcesby causing the apparatus to select, based on a hopping pattern,different narrowband regions for different subframes.
 38. The apparatusof claim 35, wherein the instructions cause the apparatus to determinethe resources by causing the apparatus to select, based on a hoppingpattern, a different single tone for transmitting the one or moredownlink PRSs to different wireless nodes.
 39. A non-transitorycomputer-readable medium for wireless communications includinginstructions that, when executed by a processor, cause the processor toperform operations comprising: monitoring for one or more positioningreference signals (PRSs) transmitted, from one or more base stations(BSs), within a narrowband region of a wider system bandwidth, whereintones of the one or more PRSs are repeated across at least one of:multiple symbols within a same subframe, or multiple consecutivesubframes; and estimating timing from the one or more base stationsbased on at least one of the one or more PRSs; wherein each of the oneor more PRSs is repeated across a set of the multiple symbols within thesame subframe or another subframe.
 40. A non-transitorycomputer-readable medium for wireless communications includinginstructions that, when executed by a processor, cause the processor toperform operations comprising: determining resources within a narrowbandregion of a wider system bandwidth for transmitting one or more downlinkpositioning reference signals (PRSs) to one or more wireless nodes,wherein determining the resources comprises determining the resourcesfor the one or more downlink PRSs to be repeated within the narrowbandregion; and transmitting the one or more downlink PRSs using thedetermined resources, wherein the transmitting comprises transmittingtones of the one or more downlink PRSs repeated across at least one of:multiple symbols within a same subframe, or multiple consecutivesubframes; wherein each of the one or more downlink PRSs is repeatedacross a set of the multiple symbols within the same subframe or anothersubframe.